Thermal shields for gas turbine rotor

ABSTRACT

A turbomachine including a rotor having an axis and a plurality of disks positioned adjacent to each other in the axial direction, each disk including opposing axially facing surfaces and a circumferentially extending radially facing surface located between the axially facing surfaces. At least one row of blades is positioned on each of the disks, and the blades include an airfoil extending radially outward from the disk A non-segmented circumferentially continuous ring structure includes an outer rim defining a thermal barrier extending axially in overlapping relation over a portion of the radially facing surface of at least one disk, and extending to a location adjacent to a blade on the disk A compliant element is located between a radially inner circumferential portion of the ring structure and a flange structure that extends axially from an axially facing surface of the disk.

STATEMENT REGARDING FEDERALLY SPONSORED DEVELOPMENT

Development for this invention was supported in part by Contract No.DE-FC26-05NT42644, awarded by the United States Department of EnergyAccordingly, the United States Government may have certain rights inthis invention.

FIELD OF THE INVENTION

The present invention relates to turbomachines and, more particularly,to a thermal shield for rotors in turbomachines.

BACKGROUND OF THE INVENTION

A gas turbine engine generally includes a compressor section, acombustor section, a turbine section and an exhaust section. Inoperation, the compressor section may induct ambient air and compress itThe compressed air from the compressor section enters one or morecombustors in the combustor section The compressed air is mixed with thefuel in the combustors, and the air-fuel mixture can be burned in thecombustors to form a hot working gas. The hot working gas is routed tothe turbine section where it is expanded through alternating rows ofstationary airfoils and rotating airfoils and used to generate powerthat can drive a rotor. The expanded gas may then exit the enginethrough the exhaust section.

During operation of the engine, various components in the engine aresubjected mechanical and thermal stresses that may reduce the mechanicalintegrity of the components over a period of engine operating time Inthe compressor section, areas of the rotor that are not covered by theblades may be protected by thermal shields. The thermal shields aretypically formed as segments supported at individual mounting points onthe rotor for retaining the segments in circumferential and radialpositions around the circumference of the rotor.

SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a turbomachine isprovided comprising a rotor having an axis and a plurality of diskspositioned adjacent to each other in the axial direction, each diskincluding opposing axially facing surfaces At least one row of blades ispositioned on each of the disks, each row of blades extending radiallyoutward from a radially facing surface of a respective disk. Acircumferentially continuous ring structure defines a thermal barrierextending axially between and overlapping the radially facing surfacesof two adjacent disks. A compliant element is located between a radiallyinner circumferential portion of the ring structure and an axiallyextending flange structure of one of the disks.

The ring structure may have an outer axially extending rim, a radiallyinner foot portion forming the radially inner circumferential portion ofthe ring structure, and a radially extending web that is axiallynarrower than and forms a connection between the rim and the footportion wherein the compliant element can movably support the footportion on the flange structure.

A retention plate structure may be detachably fastened to the disk toengage the foot portion for axially retaining the ring structure to theflange structure.

The foot portion may include an axial extension for engagement with anaxially facing surface of the disk.

The axial extension may form an anti-rotation feature havingcircumferentially facing surfaces located in engagement with cooperatingcircumferentially facing surfaces formed on the facing surface of thedisk.

Axially extending air passages may extend through the compliant elementto provide passage of air between the foot portion and the flangestructure, and the ring structure can include an outer rim having edgeslocated adjacent to edges of the blades, wherein a gap may be definedbetween the adjacent edges of the outer rim and the blades for passageof a cooling air flow from a radially inner to a radially outer locationrelative to the outer rim.

The compliant element may be a circular wave spring.

The disks may be formed of a first material and the ring structure maybe formed of a second material, which shields the radially facingsurfaces of the disks from the temperature of a hot gas passing throughan axial gas flow path containing the blades, and the second materialmay have a higher heat resistance than the first material.

The compliant element may be located at one of. a) between a radiallyinward facing side of the ring structure and a radially outward facingside of the flange structure, and b) between a radially outward facingside of the ring structure and a radially inward facing side of theflange structure.

In accordance with another aspect of the invention, a turbomachine isprovided comprising a rotor having an axis and a plurality of diskspositioned adjacent to each other in the axial direction, each diskincluding opposing axially facing surfaces and a circumferentiallyextending radially facing surface located between the axially facingsurfaces At least one row of blades is positioned on each of the disks,the blades including a platform extending axially across a portion ofthe radially facing surface of a respective disk, and the bladesincluding an airfoil extending radially outward from the platform. Anon-segmented circumferentially continuous ring structure includes anouter rim defining a thermal barrier extending axially from an edge of afirst platform on a first disk to an edge of a second platform on anadjacent second disk The outer rim overlaps a portion of the radiallyfacing surfaces of the two adjacent disks. A compliant element islocated between a radially inner circumferential portion of the ringstructure and a flange structure that extends axially from an axiallyfacing surface of one of the disks.

The radially inner circumferential portion of the ring structure may beformed by a foot portion that is connected to the outer rim by a web,defining a generally T-shaped cross-section for the ring structure, andthe web extends radially in axially spaced relation from adjacentaxially facing surfaces of the adjacent disks.

The ring structure may be non-rigidly supported to one of the disks topermit cooling air to flow radially outward along either side of theweb, from the foot portion to the outer rim, and through gaps betweenthe outer rim and the edges of the first and second platforms into anaxial gas flow path of the turbomachine.

The compliant element may maintain air passages therethrough to permitthe cooling air to pass from one side of the web to the other

The compliant element may permit a circumference of the ring structureto move radially relative to a circumference of the disk.

The ring structure may be assembled to the flange structure of the diskby axial movement of the ring structure relative to the disk, and thering structure may be retained to the disk by a retention platestructure detachably fastened to the disk.

In accordance with a further aspect of the invention, a turbomachine isprovided comprising a rotor having an axis and a plurality of diskspositioned adjacent to each other in the axial direction, each diskincluding opposing axially facing surfaces and a circumferentiallyextending radially facing surface located between the axially facingsurfaces At least one row of blades is positioned on each of the disks,and the blades include an airfoil extending radially outward from thedisk. A non-segmented circumferentially continuous ring structureincludes an outer rim defining a thermal barrier extending axially inoverlapping relation over a portion of the radially facing surface of atleast one disk, and extending to a location adjacent to a blade on thedisk. A compliant element is located between a radially innercircumferential portion of the ring structure and a flange structurethat extends axially from an axially facing surface of the disk.

The radially inner circumferential portion of the ring structure may beformed by a foot portion that is connected to the outer rim by a web,and the web extends radially in axially spaced relation from the axiallyfacing surface of the disk.

The ring structure can be non-rigidly supported to the disk to permitcooling air to flow radially in a space between the web and the axiallyfacing surface, from the foot portion to the outer rim, and through agap between the outer rim and the blade into an axial gas flow path ofthe turbomachine.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the present invention, it is believed that thepresent invention will be better understood from the followingdescription in conjunction with the accompanying Drawing Figures, inwhich like reference numerals identify like elements, and wherein

FIG. 1 is a partial cross-sectional view of a turbine engineillustrating aspects of the present invention,

FIG. 2 is an enlarged cross-sectional view of downstream disks for acompressor of the turbine engine, illustrating aspects of the invention;

FIG. 3 is an exploded perspective view illustrating aspects of theinvention;

FIG. 4 is an elevation view showing an axial face of a disk includingaspects of the invention;

FIG. 5 is a cross-sectional radial view of an anti-rotation feature inaccordance with aspects of the invention; and

FIG. 6 is an enlarged cross-sectional view similar to FIG. 2 showing analternative configuration illustrating aspects of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description of the preferred embodiment,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration, and not by way oflimitation, a specific preferred embodiment in which the invention maybe practiced. It is to be understood that other embodiments may beutilized and that changes may be made without departing from the spiritand scope of the present invention.

Referring to FIG. 1, a rotor 10 of a turbomachine 11, depicted herein asa gas turbine engine, is illustrated and includes a compressor section12, a middle section 14 extending through a combustor section of theengine, and a turbine section 16 The rotor 10 is supported for rotationabout a rotor axis 20 wherein the rotor 10 rotates in response to hotgases provided from combustors (not shown) in the middle section 14expanding through the turbine section 16 Rotation of the rotor 10 causesblades 22 (FIG. 2) in the compressor section 12 to rotate and compressair through successive stages of the compressor section 12 An identifiedsection 18 of the compressor section 12 identifies the high pressure andoutput stages of the compressor section 12 where the air, flowing in thedirection 24 through a flow path 26 defined between an outer wall (notshown) and the rotor 10, comprises a highly compressed relatively hotgas.

Referring additionally to FIG. 2, the rotor 10 is formed in thecompressor section 12 by a plurality of disks 28 positioned adjacent toeach other in the axial direction Aspects of the present invention willbe described below with specific reference to the last two disks 28 ofthe compressor section 12, identified as 28A, 28B However, it should beunderstood that the present invention in not limited to the particulardescribed rotor location and described turbomachine, and the inventioncan be located at a section of the rotor in another part of the engineor in another type of turbomachine.

As seen in FIG. 2, each disk 28 includes opposing axially facingupstream and downstream surfaces 30A, 30B, respectively. Acircumferentially extending outer surface 32 is located between theaxially facing surfaces 30A, 30B and faces radially outward toward theflow path 26 A slot 34 may be formed radially into each disk 28 at theouter surface 32, and the blades 22 can be secured into the disks 28 atthe slots 34, to define a row of blades 22 mounted to each disk 28. Theblades 22 can comprise an airfoil 36 that extends radially into the flowpath 26 In the illustrated embodiment, the blades comprise an airfoil36, and a platform 38 located at the radially inner end of each blade 22that extends axially in overlapping relation over at least a portion ofthe outer surface 32, axially upstream and downstream of a respectiveslot 34, and the platform can form a part of an inner boundary for theflow path 26.

A separate thermal barrier structure 40 is provided between at leastsome of the adjacent disks 28, and is depicted specifically with thedownstream adjacent disks 28A, 28B, also identified as first and seconddisks 28A, 28B. In accordance with an aspect of the invention, thethermal barrier structure 40 is depicted as including an upstream,non-segmented circumferentially continuous ring structure 40A betweenthe adjacent disks 28A, 28B, see also FIG. 3. The ring structure 40Aincludes an outer rim 42 defining a thermal barrier extending betweenadjacent rows of blades 22 and, in the particular illustratedembodiment, the outer rim 42 extends axially from a downstreamcircumferentially extending edge 44B of a first platform 38A on a bladerow associated with the first disk 28A to an upstream circumferentiallyextending edge 44A of a second platform 38B on a blade row associatedwith the adjacent second disk 28B. The outer rim 42 overlaps a portionof the outer surfaces 32 of two adjacent disks 28 and includes opposingcircumferentially extending axial edges 42A, 42B located adjacent to theblades 22, depicted as respective edges 44B, 44A of the platforms 38A,38B.

The ring structure 40A additionally includes a radially inner side 46formed by a radially inner circumferential portion defining a footportion 48. The foot portion 48 is connected to the outer rim by aradially extending web 50. The web 50 is connected to the outer rim 42at a central location between the edges 42A, 42B to define a generallyT-shaped cross-section for the ring structure 40A The T-shapedcross-section preferably configures the ring structure 40A as balancedfor centrifugal forces in the axial direction to avoid distortion of theouter rim 42 during operation, such as to avoid distortion of the outerrim 42 into a conical shape as a result of unbalanced centrifugal forcesat the connection with the web 50.

The ring structure 40A is preferably formed from a different materialthan that of the disks 28. That is, the disks 28 may be formed of afirst material and the ring structure 40A may be formed of a secondmaterial that has a higher heat resistance than the first material andthat can shield the outer surfaces 32 of the disks 28 from thetemperature of a hot gas passing through the flow path 26 For example,the disks 28 may be formed of a ferritic steel material and the ringstructure 40A may be formed of a superalloy, such as a nickel-basedsuperalloy material. Hence, the relatively smaller volume of the moreexpensive superalloy material may be used to form the thermal barrierdefined by the ring structure 40A, and the relatively larger volume ofthe disks 28 may be comprised of the less expensive ferritic steelmaterial.

It may be understood that as a result of the ring structure 40A beingformed out of a different material and with a different structuralconfiguration than the disks 28, thermal or structural movement, such ascircumferential expansion, of the ring structure 40A can differ fromthat of each of the adjacent disks 28. In accordance with a furtheraspect of the invention, the ring structure 40A is non-rigidly supportedto only one of the disks 28 by a compliant interface structure, and inthe illustrated embodiment is located relative to the second disk 28B bya compliant interface structure. In particular, the ring structure 40 acan be supported on the second disk 28B by a compliant interfacestructure comprising a compliant element 52 located between the radiallyinward facing inner side 46 of the ring structure 40A and a radiallyoutward facing side of the disk 28B defined by a circumferentialupstream flange structure 54A that extends axially from the upstreamaxially facing surface 30A of the disk 28B. The flange structure 54A, asdefined herein, can comprise an axially extending surface formed on adisk 28 that faces in the radial direction. The compliant element 52 canpermit limited movement of the ring structure 40A relative to the outersurfaces 32 of the adjacent disks 28A, 28B, such as may be caused by adifferent thermal expansion and differential radial strain due torotation loads resulting in a change of the circumference of the outerrim 42 relative to the circumference(s) defined by the outer surfaces 32of the adjacent disks 28A, 28B.

Referring to FIGS. 3 and 4, the compliant element 52 is preferablyformed of a resilient material, and can be formed by an annular elasticelement, such as a circular wave spring (otherwise known in the art as a“Marcel expander”). The compliant element 52 is positioned around andsupported on a radially outer surface 56 of the flange structure 54A,and provides a resilient support extending within a gap 58 between theradially inner side 46 of the ring structure 40A and the radially outersurface of the flange structure 54A Hence, the compliant element 52 canpermit transient and steady-state radial displacement of the outer rim42 of the ring structure 40 a independently of the adjacent disks 28A,28B, and provides a reduced contact force with a corresponding reducedstress to both the outer rim 42 and the disks 28A, 28B It may also benoted that, since the ring structure 40A is mounted to only one of theadjacent disks 28A, 28B, a load path is not created between the adjacentdisks 28A, 28B, permitting a greater degree of freedom between the disks28A, 28B for movement in both the radial direction and the axialdirection.

As seen in FIG. 4, the non-rigid mounting of the ring structure 40A tothe disk 28B additionally permits cooling air to flow axially betweenthe foot portion 48 and the flange structure 54A. In particular, thecompliant element 52 defines passages 60 that are maintained between theundulations of the wave spring. Cooling air can be provided from aradially inner location, such as from an upstream location adjacent tothe middle section 14 of the rotor 10, as depicted by cooling air flow62 in FIG. 2 The web 50 is located in spaced relation to each of theadjacent axially facing surfaces 30A, 30B, and the cooling air can flowradially outward along either side of the web 50, from the foot portion48 to the outer rim 42. A first portion 64A of the cooling air can flowgenerally directly radially outward along one side of the web 50, and asecond portion 64B of the cooling air can pass axially through thepassages 60 to flow radially outward along the other side of the web 50,between the web 50 and the axially facing surface 30A. The first andsecond portions 64A, 64B of cooling air flows radially outward throughgaps between the edges 42A, 42B of the outer rim 42 and the blades 22 toprovide cooling to the blade surfaces at the rim edges 42A, 42B. In theparticular illustrated embodiment, the cooling air can flow out betweenthe rim edges 42A, 42B and the respective edges 44B, 44A of the firstand second platforms 38A, 38B into the gas flow path 26 of thecompressor section 12, providing cooling to the outer surfaces of theplatforms 38A, 38B adjacent to the outer rim 42.

It may be understood that, since the ring structure 40A is a continuousring, i e., a 360° structural ring, assembly of the ring structure 40Ato the disk 28B requires that it be mounted through axial placement ontothe flange structure 54A during assembly of the disks 28 forming therotor 10. That is, mounting the ring structure 40A comprises moving thering structure 40A axially onto the flange structure 54A toward theaxially facing surface 30A As seen in FIG. 2, the foot portion 48includes axial extension portions 66 that engage the axially facingsurface 30A to space the web 50 from the axially facing surface 30A. Inaddition, the ring structure 40A can be maintained on the flangestructure 54A by circumferentially spaced retention plates 68, see alsoFIG. 4, that may be detachably fastened to the disk 28B, and in theillustrated embodiment, can be fastened to an axial end 70 of the flangestructure 54A by fasteners, such by as bolts 72.

The extension portions 66 are preferably discrete elements that arelocated at circumferentially spaced locations around the foot portion48. By providing both the retention plates 68 and the extension portions66 as discontinuous or spaced elements, openings are defined for passageof the cooling air in the axial direction past the retention plates 68into the gap 58 and radially outward past the extension portions 66.

Referring to FIG. 5, the extension portions 66 may additionally compriseanti-rotation features for cooperating with corresponding features onthe axially facing surface 30A. For example, each extension portion 66can be formed as a plurality of ridges or teeth 74 cooperating withcorresponding ridges or teeth 76 formed on the axially facing surface30A. In the illustrated embodiment, it can be seen the locations of thecooperating teeth 74, 76 may be spaced circumferentially, such as spaced90°, around the axially facing surface 30A (FIG. 3). Since, the ringstructure 40A is non-rigidly supported on the flange structure 54A, thering structure 40A could freely rotate relative to the disk 28B withoutthe presence of the anti-rotation feature. The cooperating teeth 74, 76include respective circumferentially facing surfaces 74 a, 76 a thatengage each other to ensure that the ring structure 40A rotates with thedisk 28B, without restricting radial movement, e g., thermal movement,of the ring structure 40A relative to the disk 28B.

Referring to FIG. 2, the disk 28B can comprise a last disk 28 in thecompressor section 12 and is located adjacent to a stationary compressoroutlet structure 78. A circumferential downstream flange structure 54Bextends from the downstream axial facing surface 30B, and the thermalbarrier structure 40 can further include a downstream, non-segmentedcircumferentially continuous ring structure 40B associated with thedownstream flange structure 54B.

The ring structure 40B can be formed similar to the ring structure 40Aand includes a foot portion 48 joined to an outer rim 42 by a web 50.The ring structure 40B can be maintained in position relative to theflange structure 54B by a compliant element 52, such as a circular wavespring. Additionally, the ring segment 40B can be maintained in positionby retention plates 68 and can include extension portions 66 formed as acircumferentially discontinuous element and incorporating anti-rotationfeatures, as described above for the ring structure 40A.

The outer rim 42 of the ring structure 40B extends forward inoverlapping relation over a portion of the outer surface 32 of the disk28B to provide thermal protection to the outer surface 32 As describedabove for the ring structure 40A, cooling air can pass through thecompliant element 52, between the foot portion 48 and the flangestructure 54B, and then radially outward between the downstream axiallyfacing surface 30B and the web 50 to provide a cooling air flow througha gap between the outer rim 42 and the blade 22. In particular, in theillustrated embodiment, the cooling air can pass between an upstreamedge 44A of the outer rim 42 and a downstream edge 44B of a platform 38Bfor the blade row on the disk 28B.

Additionally, in the illustrated embodiment, the downstream side of theweb 50 for the ring structure 40B can be provided with a pair ofradially spaced flange members 80, 82 located adjacent to cooperatingseal structure 84, 86 on the outlet structure 78. The flange members 80,82 and cooperating seal structure 84, 86 form a labyrinth seal forlimiting passage of cooling air at the downstream side of the ringstructure 40B.

Referring to FIG. 6, an alternative configuration of the invention isillustrated in which elements corresponding to elements described abovewith reference to FIGS. 2-5 are identified with the same referencenumerals increased by 100. In the embodiment of FIG. 6, the ringstructure 140A is positioned to the disk 128B by cooperation between thefoot portion 148 at a radially inner circumferential portion of the ringstructure 140A and a flange structure 154 located radially outward fromthe foot portion 148. Specifically, a compliant element 152, e.g., acircular wave spring, can be positioned between a radially outwardfacing side 155 of an axial extension portion 166 of the foot portion148 and a radially inward facing surface 157 of the flange structure 154to locate the ring structure 140A in the radial direction relative tothe disk 128B.

The ring structure 140A can be axially retained to the disk 128B by aplurality of circumferentially spaced retention plates 168. Inaccordance with an aspect of the invention, each retention plate 168 caninclude a radial portion 168A for engaging an axial face of the footportion 148, and an axial portion 168B extending across the inner sideof the foot portion 148 to engagement with the disk 128B, where theaxial portion 168B can be detachably fastened to the disk 128B It may benoted that the axial portion 168B preferably extends in radially spacedrelation to the foot portion 148 to avoid a rigid radial restraintbetween the disk 128B and the ring structure 140A.

The axial extension portions 166 and retention structures 168 arepreferably circumferentially spaced along the axially facing surface130A, i e, form circumferentially discontinuous structures, to permitcooling air to flow radially outward to pass through the compliantelement 152 and between the web 150 and the axially facing surface 130A,as depicted by air flow 164B At the radially outer end of the web 152,the cooling air can pass between the outer rim 142 and the outer surface132 of the disk 128B, and further pass between the edge 142B of theouter rim 142 and a blade (not shown in FIG. 6) In addition, it may beunderstood that a downstream rib structure similar to the rib structure40B may be provided associated with the disk 128B, and including acompliant interface structure similar to the interface described for thering structure 140A.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A turbomachine comprising: a rotor having an axisand a plurality of disks positioned adjacent to each other in an axialdirection, each disk including opposing axially facing surfaces; atleast one row of blades positioned on each of the plurality of disks,each row of blades extending radially outward from a radially facingsurface of a respective disk of the plurality of disks; acircumferentially continuous ring structure defining a thermal barrierextending axially between and overlapping the radially facing surfacesof two adjacent disks of the plurality of disks; a compliant elementcomprising an annular elastic element located between a radially innercircumferential portion of the ring structure and an axially extendingflange structure of one of the two adjacent disks, wherein the ringstructure has an outer axially extending rim, a radially inner footportion forming the radially inner circumferential portion of the ringstructure, and a radially extending web that is axially narrower thanthe foot portion and forms a connection between the rim and the footportion wherein the compliant element movably supports the foot portionto the flange structure; a retention plate structure detachably fastenedto the disk to engage the foot portion for axially retaining the ringstructure to the flange structure, wherein the foot portion includes anaxial extension for engagement with one of the axially facing surfacesof the plurality of disks, wherein the axial extension forms ananti-rotation feature having circumferentially facing surfaces boated inengagement with cooperating circumferentially facing surfaces formed ona facing surface of the disk; and axially extending aft passages throughthe compliant element providing passage of air between the foot portionand the flange structure, and the ring structure including an outer rimhaying edges boated adjacent to edges of the blades, wherein a gap isdefined between the adjacent edges of the outer rim and the blades forpassage of a cooling air flow from a radially inner to a radially outerlocation relative to the outer rim.
 2. The turbomachine of claim 1,wherein the compliant element is a circular wave spring.
 3. Theturbomachine of claim 1, wherein the disks are formed of a firstmaterial and the ring structure is formed of a second material, whichshields the radially facing surfaces of the disks from the temperatureof a hot gas passing through an axial gas flow path containing theblades, and the second material having a higher heat resistance than thefirst material.
 4. The turbomachine of claim 1, wherein the compliantelement is located at one of: between a radially inward facing side ofthe ring structure and a radially outward facing side of the flangestructure; and between a radially outward facing side of the ringstructure and a radially inward facing side of the flange structure.